From electric field catalysis to plasma catalysis: A combined experimental study and kinetic modeling to understand the synergistic effects in methane dry reforming

The combination of external fields and catalysts is considered a promising method for enhancing the performance of dry reforming of methane (DRM). In this study, thermal, electric field, and plasma assisted catalytic DRM were implemented to investigate the synergistic effect between the electric field/plasma and the catalyst. Experimental measurements and chemical kinetics modeling were combined to unveil the underlying mechanism of non-equilibrium molecular excitation in external fields (electric field and plasma) and catalyst synergistic DRM. The experimental results showed that introducing an electric field can improve the reaction activity in low- temperature regions compared to thermal catalysis. However, plasma catalysis exhibits a significant enhancement effect than electric field catalysis. Plasma catalysis achieved CH4 and CO2 conversion of 30.9 % and 23.2 %, respectively, at 7000 V and 500 degrees C, while the highest conversion for electric field catalysis were 20.5 % and 16.2 %, respectively. A zero-dimensional kinetic simulation was conducted using a hybrid ZDPlasKin-CHEMKIN model to predict the species densities over time, simultaneously including electric field- and plasma-induced reactions and surface reactions. The numerical model presented good agreement with the results of CH4/CO2 consumption and products (syngas and hydrocarbons) formation. Path flux analysis shows that the vibrationally excited CO2(v) promotes the dissociative adsorption in electric field catalysis. However, plasma-generated radicals, ions, and electronically excited species significantly enhance gas-phase and E-R reactions in plasma catalysis. The dominant reaction mechanism for syngas formation and reactants consumption shifts from surface reactions to gas-phase reactions as the system transitions from electric field catalysis to plasma catalysis. This work provides new insights into the synergistic effects between the external fields (electric field and plasma) and the catalyst in DRM process.